Nellie Ohr, the wife of Justice Department official Bruce Ohr, claimed spousal privilege on Friday in order to avoid certain questions from House Republicans about the controversial anti-Trump dossier.

While describing her as cooperative in the voluntary appearance, Republican and Democratic lawmakers told Fox News that Ohr took spousal privilege, which Republicans said did not allow them to get to core questions about the salacious dossier, and how it got into the hands of the FBI.

Nellie Ohr worked for Fusion GPS, the research group that commissioned the dossier.

Glenn Simpson, Fusion GPS’ co-founder, earlier this week invoked his Fifth Amendment right not to answer questions during a separate Capitol Hill appearance before congressional investigators. Bruce Ohr has previously testified about his contact with Simpson during the 2016 presidential campaign.

The dossier, authored by former British spy Christopher Steele and commissioned by Fusion GPS, was paid for by the Democratic National Committee and Hillary Clinton's presidential campaign through law firm Perkins Coie. It included salacious and unverified allegations about Trump's visit to Russia before he was president and has become a central focus as lawmakers investigate the origins of the Russia investigation.

The Ohrs’ role also has become a key focus for Republican congressional investigators as they investigate the origin of the FBI's Russia investigation. They alleged in a January 2018 House Intelligence Committee FISA memo that Ohr was the backchannel for Steele after he was fired by the bureau in November 2016 over his contacts with the media.

Bruce Ohr previously told the FBI about his wife’s work for Fusion GPS, as well as his reservations about the credibility of the document and Steele’s animus for then-candidate Donald Trump. However, this was not shared with the Foreign Intelligence Surveillance Court when the dossier was used to help secure a surveillance warrant for then-Trump campaign aide Carter Page.

Congressional Republicans argue the dossier was improperly used to obtain that warrant and subsequent renewals.

Fox News' Adam Shaw and Alex Pappas contributed to this report.

Catherine Herridge is an award-winning Chief Intelligence correspondent for FOX News Channel (FNC) based in Washington, D.C. She covers intelligence, the Justice Department and the Department of Homeland Security. Herridge joined FNC in 1996 as a London-based correspondent.